As it is well known, in the continuous research aimed to maximize the utilization of the electric power which is employed for normal human activities, the recovery of the heat, being produced as a secondary effect in these activities, is one of the keypoints to optimize the energy rendering and also to reduce the total power consumption in any kind of apparatus.
For this reason, several systems have been studied over the years, usually indicated as “scavengers”, which are able to recover the heat generated by an operation performed by using electric energy.
Many known solutions, unfortunately, have a low efficiency value (for a maximum of around 10%), calculated as the amount of recovered heat, taking into account of the overall quantity of available heat.
It has been observed that solutions based on the Seebeck's effect are typically more efficient in term of energy balance because they allow a one-way and direct transformation of the heat into electric power.
The Seebeck's effect is in fact a thermoelectric effect providing a direct conversion of temperature differences into an electric voltage.
In particular, since metals respond differently to temperature, it is possible to create a current loop, when a closed loop is formed of two metals being joined and having opposite ends in two places with a temperature difference. In fact, a voltage is created in the presence of a temperature difference between two different metals or semiconductors, a continuous current then flowing in the conductors if they form a complete loop.
The Seebeck's effect is commonly used in a device called thermocouple (because it is made from a coupling or junction of materials, usually metals) to directly measure a temperature difference or to measure an absolute temperature by setting one of its ends to a known temperature.
A thermocouple based on the Seebeck's effect may be also used, working in an opposite way, for the production of electrical power by converting a gradient of temperatures into electricity, thus being an efficient system for recovering heat, as above indicated.
Also efficient systems based on the Seebeck's effect are, however, bound by the underlying physical principle which is linked to the physical-chemical nature of the materials being used to form the thermocouple, and also depends on the difference of temperatures between the thermocouple ends, such that the problem of a low efficiency may also arise in these systems.